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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Bug - calculating powers of constants smaller than 1.0e-5 in user-defined functions should work</title>
<link rel="stylesheet" href="../../../resources/js-test-style.css"/>
<script src="../../../js/js-test-pre.js"></script>
<script src="../../../js/webgl-test-utils.js"></script>
</head>
<body>
<canvas id="canvas" width="256" height="256"> </canvas>
<div id="description"></div>
<div id="console"></div>
<script id="vshader" type="x-shader/x-vertex">
attribute vec3 aPosition;

void main() {
    gl_Position = vec4(aPosition, 1);
}
</script>
<script id="fshader" type="x-shader/x-fragment">
precision highp float;

float fun(float arg) {
    // These values are still easily within the highp range.
    // The minimum range in terms of 10's exponent is around -19 to 19, and IEEE-754 single precision range is higher than that.
    return 1.0e12 * pow(arg, 2.0);
}

void main() {
    // Note that the bug did not reproduce if an uniform was passed to the function instead of a constant,
    // or if the expression was moved outside the user-defined function.
    const float a = 1.0e-6;
    float b = fun(a);
    if (abs(b - 1.0) < 0.01) {
        gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0); // green
    } else {
        gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0); // red
    }
}
</script>
<script type="application/javascript">
"use strict";
description();
debug("");
var wtu = WebGLTestUtils;
function test() {
  var gl = wtu.create3DContext("canvas");
  if (!gl) {
    testFailed("context does not exist");
    return;
  }
  if (gl.getShaderPrecisionFormat(gl.FRAGMENT_SHADER, gl.HIGH_FLOAT).precision == 0) {
    testPassed("highp precision not supported");
  } else {
    wtu.setupUnitQuad(gl);
    var program = wtu.setupProgram(gl, ["vshader", "fshader"], ["aPosition"], undefined, true);
    wtu.drawUnitQuad(gl);
    wtu.checkCanvasRect(gl, 0, 0, 256, 256, [0, 255, 0, 255]);
  }
};

test();
finishTest();
</script>
</body>
</html>

